Field of the invention
The present invention relates to a lens barrel that is mounted on an image pickup apparatus, such as a digital camera or a film camera, an image pickup apparatus equipped with the lens barrel, and an image blur correction device.
Description of the Related Art
Among image pickup apparatuses including a digital camera, a type that performs a zooming operation by changing the spacing between lens groups of a lens barrel in an optical axis direction has come into widespread use. In general, within the lens barrel, there are provided a shutter mechanism, a diaphragm mechanism, an image blur correction device, and the like, each of which moves in an optical axis direction according to the zooming operation, and a flexible printed circuit board is used as means for supplying electric power to an actuator that drives these.
Incidentally, the image blur correction device is provided with a Hall element for detecting the amount of movement of an image blur correction lens. The Hall element is mounted on the flexible printed circuit board for supplying electric power to the image blur correction device, and is positioned and fixed on a component part of the image blur correction device, together with the flexible printed circuit board.
In order to accurately detect the amount of movement of the image blur correction lens, it is important to fix the Hall element at a desired location. For this reason, the flexible printed circuit board and the Hall element are required to be properly fixed to the image blur correction device.
As a method of fixing the flexible printed circuit board to the image blur correction device, there has been proposed, for example, a technique in which the flexible printed circuit board is provided with a Hall element-mounting section on which the Hall element is mounted and two positioning holes for positioning the flexible printed circuit board with respect to the image blur correction device (technique to which the invention of Japanese Patent Publication No. 4921087 is related). In this technique, the flexible printed circuit board is positioned with respect to the image blur correction device by causing the positioning holes of the flexible printed circuit board to be engaged with respective positioning shafts provided on the image blur correction device, and the Hall element is fixed to the image blur correction device.
In the technique to which the invention of Japanese Patent Publication No. 4921087 is related, the flexible printed circuit board has its position restricted by being engaged with the image blur correction device, and the Hall element has its position restricted by being fixed to the image blur correction device. Therefore, the Hall element mounted on the flexible printed circuit board is positioned not only with respect to the flexible printed circuit board, but also with respect to the image blur correction device. In short, the Hall element has its position restricted by dual positioning means.
In positioning the Hall element, it is required to take into account a positional deviation due to a mounting error caused when the Hall element is mounted on the flexible printed circuit board, dimensional tolerances of fixing portions of the image blur correction device and the Hall element, dimensional tolerances of engaging portions of the flexible printed circuit board and of the image blur correction device, and so forth.
For example, a location where the Hall element and the image blur correction device are fixed to each other and a location where the flexible printed circuit board and the image blur correction device are engaged with each other is sometimes positioned further away from each other than required due to the above-mentioned factors causing the positional deviation. In this case, the length of a portion of the flexible printed circuit board, which is required to extend between the location of engagement of the flexible printed circuit board and the image blur correction device and the location of fixing of the Hall element to the image blur correction device becomes insufficient.
Therefore, if an attempt is made to forcefully fixing the Hall element to the image blur correction device because the Hall element does not reach the location where it is to be fixed to the image blur correction device, the Hall element or the fixing portion of the image blur correction device can be broken or unnecessary load is applied to the mounting portion of the flexible printed circuit board, causing separation of the Hall element.
On the other hand, if the length of the portion of the flexible printed circuit board becomes too long for a dimension between the location of engagement of the flexible printed circuit board and the image blur correction device and the location of fixing of the Hall element to the image blur correction device, this leads to floating or looseness of the flexible printed circuit board. In this case, there is a fear that the flexible printed circuit board can interfere with neighboring component parts during a zooming operation of the lens barrel and adversely affect the zooming operation.